This document discusses cerebrovascular malformations (CVMs) of the brain. It describes that CVMs are disorders representing morphogenetic errors affecting brain arteries, capillaries or veins. It classifies CVMs into two main groups - vascular malformations and hemangiomas. Pial arteriovenous malformations (AVMs) are specifically discussed. Pial AVMs have direct connections between arteries and veins without an intervening capillary bed. They contain enlarged feeding arteries, a nidus of tangled vascular channels, and dilated draining veins. Imaging findings on CT, MRI and cerebral angiography are provided to identify the key components of pial AVMs. Differential diagnoses and clinical management are also reviewed.

1. Dr. Manmohan Bir
Shrestha
FOR RADIOLOGY
MAC

2. Vascular Malformations in Brain
OVERVIEW
 Cerebrovascular malformations (CVMs) are a
heterogenous group of disorders that represent
morphogenetic errors affecting arteries, capillaries,
veins or various combinations of vessels.

3. Using accurate terminology
 2 major groups:
A. Vascular malformations
 Includes AVM & Fistula
B. Hemangiomas
 These are benign vascular neoplasms, not malformations
 Proliferating, mesenchymal, nonmeningothelial tumors
 Can be capillary or cavernous

4. Classification of Cerebrovascular
malformations
A. Histopathologic classification
B. Functional classification

5. A.Histopathologic classification
I. Arteriovenous malformation
II. Venous angioma
III. Capillary telangiectasia
IV. Cavernous malformation.

6. B. Functional classification
 Endovascular radiologists have proposed a functional,
highly practical system, and divides all CVMs in 2
categories
 CVMs that display shunting
 AVM
 Fistula
 CVMs without AV shunting
 Everything else
 i.e. venous, capillary, cavernous malformations.
The 1st group are amenable to intervention & latter are either left
alone or treated surgically.

8. Pial AVM
• Also called Cerebral AVM/ Classic AVM
• Definition
• It is a vascular malformation with direct artery to vein (AV)
shunting, no intervening capillary bed
• 3 components
• Enlarged feeding arteries, 1 or more
• Nidus of tightly packed, enlarged tangled vascular channels
• Dilated draining veins, 1 or more
**No normal brain parenchyma in between

11. Demographics
 Age
 Peak presentation: 20-40 years
 Gender
 M=F
 Epidemiology
 Prevalence: 0.040 - 0.52%

12.  Location
 Supratentorial – 85%
 Posterior fossa – 15%
 Number
 Solitary
 Multiple AVMs usually syndromic
 (Hereditary hemorrhagic telangiectasia,
Wyburn-Mason syndrome).
 Size
 Varies from microscopic to giant
 Most symptomatic AVMs are 3-6 cm.

13. Pathology
 Etiology
 Origin of AVMs remain uncertain
 However, thought to occur congenitally, due to dysregulated
angiogenesis.
 Genetic
 Sporadic AVMs have up/down-regulated genes
 Homeobox genes, such as HOXD3 AND HOXB3
 Pleomorphisms on p21 locus of chromosome 9
 Syndromic
 Hereditary hemorrhagic telangiectasia
 Wyburn-Mason syndrome

14. Clinical presentation
 Headache
 Seizure
 Focal neurological deficit
 Hemorrhage
 Parenchymal/subarachnoid/intraventricular
 Ischaemic events due to vascular steal from normal
brain
 Incidental finding

15. Imaging
 CT
 MRI
 Angiography

16. CT
 NECT
 Normal, if AVM is very small
 Iso/hyperdense serpentine vessels
 Calcification in 25-30%
 AVM bleed = parenchymal/intraventricular/subarachnoid
hemorrhage
 Post-embolization – embolics appear hyperdense within
nidus
 CECT
 Strong enhancement of arterial feeders, nidus and draining
veins, giving appearance of “bag of worms”
 CTA
 Depicts enlarged arteries, draining veins

17. Case of an adult
with complaints of left sided pulsatile tinnitus
NECT

18. MIP CTA

19. Case of 40 yrs. Female
with complaints of severe headache

20. NECT

21. CECT

22. MR findings
 T1WI
 Tightly packed mass, “honeycomb” of flow voids
 Signal varies with flow rate, presence/age of hemorrhage
 T2WI
 Tangle of serpiginous, ‘honeycomb’ of flow voids
 Little/no brain inside nidus
 Some gliotic high signal may be present
 FLAIR
 Flow voids with surrounding high signal (gliosis)
 T2*GRE
 Blooming if hemorrhage
 Post Contrast T1
 Strong enhancement of nidus, draining veins
 Rapid flow may not enhance arteries, and seen as flow voids
 MRA
 Helpful for gross depiction of flow
 Does note depict detailed angioarchitecture

23. T1WI

24. T2WI

25. FLAIR

26. T1 POST CONTRAST

28. Angiographic findings
 Digital Substraction Angiography (DSA) best
delineates internal angioarchitecture
 Depicts 3 components of AVM

29. Case of 50 yrs. Male
with complaints of sudden severe
headache and left sided weakness

30. NECT

31. DSA

34. Associated abnormalities
 Flow-related aneurysm on feeding artery= 10-15%
 Intranidal aneurysm = >50%
 Vascular steal may cause ischemia in adjacent brain

35. Staging/grading
 Spetzler-Martin scale
 Score correlates with operative outcome
Score = 1-5
 Size
 Small (<3cm) =1
 Medium (3-6 cm)= 2
 Large (>6 cm) = 3
 Location
 Non-eloquent area = 0
 Eloquent area = 1
(sensorimotor cortex, visual cortex, thalamus, hypothalamus,
internal capsule, brainstem, cerebellar peduncles, deep nuclei)
 Venous drainage
 Superficial only = 0
 Deep = 1

41. Differentials for Pial AVM
 Dural AV fistula
 Glioblastoma with AV shunting

42. Dural AV fistula
 AV shunts within wall of patent+- partially
thrombosed dural venous sinus, parallel venous
channel, or adjacent cortical vein.
 Most common location = transverse/sigmoid sinus
(35-40%)
 Differentiate from pial AVM by
 Nidus intimately related to dural venous sinus
 Predominant blood supply is from dural(meningeal)
arteries>> pial artery
 Flow-related aneurysm are rare.

43. Case of AV fistula
60 yrs. Old female
with complaints of sudden severe
headache

44. NECT

45. MIP CTA

46. DSA

49. Glioblastoma with AV shunting
 GBM enhances
 Has mass effect
 Some brain parenchyma between vessels.

50. Key points
 Hemangiomas are benign vascular neoplasms, not vascular
malformations
 Pial AVMs have direct artery to vein shunting, no
intervening capillary bed
 AVM has 3 components – feeding artery, nidus & draining
veins
 Calcification in 25-30% cases
 No brain parenchyma
 No/minimal mass effect
 DSA best delineates angioarchitecture
 Flow-related aneurysm in feeding artery & nidus should be
looked carefully
 DD’s – Dural AV fistula
 Glioblastoma with AV shunting

51. THANK YOU